1. SUMMARY (Clinical Core) In support of the goals of the National Alzheimer's Project Act, the Stanford ADRC will focus on the Alzheimer's disease (AD) spectrum and the Lewy body (LB) spectrum of neurodegenerative cognitive impairment. Recognizing that critical answers will emerge more readily when investigators can delve deeply within and across multiple levels of participant data, we have adopted a strategy of deep phenotyping. Stanford ADRC participants are characterized intensively and followed over time. The AD spectrum includes cognitively impaired patients with AD dementia and mild cognitive impairment due to AD, as well as preclinical AD inferred from biomarker data. The LB spectrum encompasses dementia with Lewy bodies and Parkinson's disease dementia and Parkinson's disease patients with mild cognitive impairment. Healthy adults without cognitive or motor impairment can serve as an age-equivalent comparison population, as an asymptomatic at-risk population, and as a potential preclinical population in which mechanisms of cognitive aging and preclinical transition can be studied. Within the LB spectrum, Parkinson's disease patients without cognitive impairment serve as age-equivalent comparators and as an at-risk transitional population for the development of LB- spectrum cognitive impairment. Stanford ADRC resources will enable the parallel study of these AD and LB spectrum disorders. Opportunities for investigators to compare and contrast can provide unique insights into pathogenesis, resistance and resilience, and therapeutic approaches. The Clinical Core will be responsible for participant enrollment and for clinical, cognitive, and behavioral assessments. In support of a strategy that emphasizes the deep phenotyping of individual participants, the Clinical Core is also responsible for biospecimen procurement, imaging referral, and brain donation consent. It is responsible for participant retention and for longitudinal follow-up. Most new participants in the Stanford ADRC will be asked to provide disease-defining biomarkers measured in CSF, imaged by amyloid-PET/MRI, or both; to consent to longitudinal follow-up; and to agree to brain donation through the Neuropathology Core. The Clinical Core will work with other ADRC Cores to accomplish four aims focused on the AD spectrum and the LB spectrum of neurodegenerative cognitive impairment: (1) Enroll participants into longitudinal research protocols of the Stanford ADRC; characterize their neurological, cognitive, and behavioral status; provide consensus diagnoses; follow participants longitudinally; and promote adherence; (2) support the efforts of other ADRC Cores; (3) support ADRC development project grants and research needs of qualified externally funded investigators who could benefit from Core resources; and (4) support the Research Education Component by providing a rich training environment for medical and graduate students, residents, fellows, and junior faculty.